At primary school we sang hymns almost every day in assembly.
I remember liking some hymns more than others, some of them had potential to mess around a bit & pretend you misread the OHP. Luckily I never needed to use that excuse.
With Lord Of The Dance I sometimes tried to end the lines with an ee sound notes that Mariah Carey would struggle with.
There was the hymn with the line ending King Of Kings, with another line at the end of the verse ending with just King, but most people kept getting that wrong.
While I never got caught singing things wrong, I remember one teacher complaining that some pupils were just badly mouthing along, like a "tank of goldfish"!
Memorable mis-sings winclude "When At Knight Won At Spurs" & "Oh Lord, Come By Car".
Some songs that aren't really hymns used to be features including Yellow Submarine (often mis-sung as yellow washing machine) & The Ink Is Black, The Page Is White" (which I came up with a cheeky resung version).
At secondry school we didn't bother with hymns in assembly, apart from one time we had to sing London's Burning for about 10 minutes non-stop for no obvious reason.
The Trickster On The Roof